Copper Nanoparticles and Copper-Containing Metal-Organic Coordination Polymers in the Catalytic Amination of 2-Halopyridines

The efficiency of copper-containing metal-organic coordination polymers (Cu-MOFs) and commercially available non-immobilized copper nanoparticles (CuNPs) in the amination of 2-iodopyridine, 2-bromopyridine and its trifluoromethyl derivatives with -octylamine and adamantane-containing amines with different steric hindrances at the amino group was compared. The yields of the amination products under optimized conditions were shown to be close for both catalytic systems. To achieve good yields in the case of 2-bromopyridine, an increase in the concentration of reagents and the use of 2 equiv. of haloarene are required, while the introduction of a trifluoromethyl group at position 6 of the pyridine ring improves the yields of the amination products. Increasing steric hindrances at the amino group leads to a noticeable decrease in the yields of products in the Cu-MOF catalyzed reactions. However, the use of CuNPs allows for successful reactions with such amines, and CuNPs of 25 nm average size demonstrated an advantage over bifractional nanoparticles of 10/80 nm. On the other hand, increasing the concentration of reagents in the Cu-MOF catalyzed reactions provides good yields of the target compounds without addition ligands.